Metasurfaces and metamaterials emerged as promising nanophotonic material and device platforms to control light-matter interactions at the nanoscale. In such materials, the collective and effective optical response is dictated by individual building blocks and controlled by the geometrical parameters forming the crystal structure. In this talk, I will provide an overview of the research program in the Metamaterials and Nanophotonic Devices Laboratory at Northwestern University. I will introduce machine learning and inverse electromagnetic design methods to model optical metasurfaces. Inverse-designed free-space and on-chip metasurfaces realized with direct laser writing technique will be discussed and their applications in imaging and spectroscopy will be highlighted. Metasurface spatial filters for broadband optical edge-detection and bound-states-in-continuum (BIC) metasurfaces integrated with quantum dots will be introduced. I will also highlight collaborative research in designing and realizing metasurfaces based on DNA-assembled nanoparticle superlattices and their potential applications.